;*********************************************************
;* BUT1.ASM	Allows you to control one i/o with
;*		a pushbutton (on/off function)
;*		input at PORTD, output at PORTB
;*
;* Copyright ©2002 Rob's ElectroSoft
;*
;* RES can be reached by email: electro1@wanadoo.nl
;* Internet:  	http://Gheos.com/avr
;*
;* Version	:1.0
;* Target MCU	:AT90S1200-12PI@4MHz
;* Date		:11-06-2002
;*********************************************************

.device AT90S1200
.include "1200def.inc"


	rjmp	RESET			;reset vector




;* Main program - Command LED (on/off)

RESET:	cbi	DDRD, 2			;input
	sbi	PORTD, 2		;pull-up On
	sbi	DDRB, 2			;output
	cbi	PORTB, 2		;LED Off
	nop				;settle R=10k of reset

;* Code

wait:	cbi	PORTB, 2		;LED Off
	sbis	PIND, 2			;if lo -> LED On
	rjmp	ledon
	rjmp	wait			;else wait
	
ledon:	sbi	PORTB, 2		;LED On
	sbic	PIND, 2			;if hi -> LED Off
	rjmp	wait
	rjmp	ledon			;else keep LED On